Heat recovery system for high temperature flue gas at ammoxidation section

Abstract

A heat recovery system for high temperature flue gases at an ammoxidation section, is used for preparing sodium nitrate/sodium nitrite. An ammoxidation furnace is connected with a waste heat boiler, the waste heat boiler is communicated with an external pipe by a valve 3, a desalinizing water tank is communicated with the waste heat boiler by the valve 1, a coal economizer is added between the waste heat boiler and an alkali absorption section, the coal economizer is communicated with the desalinizing water tank by a valve 2, a pneumatic regulating valve remotely controlled by a distributed control system, is connected between the coal economizer and the desalinizing water tank in series, and the pneumatic regulating valve and a manual regulating valve are connected in parallel. The coal economizer of the invention is used for supplementing water for a boiler for heating, which increases steam production amount, enhances a heat energy utilization rate, and can effectively implement purposes of energy saving and consumption reduction; the coal economizer is used to reduce a process gas temperature, indirectly raises a sodium nitrite/sodium nitrate content ratio value in an alkali absorption liquid in an alkali absorption section, and enables a tail gas content to reach 800mg/m3, and benefits for environmental protection; and the pneumatic regulating valve is mounted on the coal economizer, and is convenient for remote control by the distributed control system.

Description

technical field [0001] The invention relates to the technical field of sodium nitrate / sodium nitrite preparation, in particular to a heat recovery system for high-temperature flue gas in an ammonia oxidation section. Background technique [0002] In the ammonia oxidation section of sodium nitrate / sodium nitrite production, the liquid ammonia is evaporated into gaseous ammonia and then mixed with air, mixed in the gaseous ammonia and air mixing filter until the ammonia content reaches 10±0.5% (volume fraction), and then sent into the ammonia In the oxidation furnace, it reacts under the platinum catalyst to generate process gas (the main component is NO X , N 2 、H 2 O), the reaction is as follows: [0003] NH 3 +O 2 →NO X +H 2 O+Q↑ (1) [0004] 4NH 3 +3O 2 →2N 2 +6H 2 O+Q↑ (2) [0005] The above reactions are all strong exothermic reactions, and the process gas (mainly composed of NO X , N 2 、H 2 O) The temperature is 800±10°C, and th...

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Problems solved by technology

Before the economizer was installed, the process gas was cooled to about 220°C after heat exchange by the waste heat boiler and sent to the alkali absorption section. Due to the high temperature of the gas,

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